THE PRODUCT OF ZFP59 (MFG2), A MOUSE GENE EXPRESSED AT THE SPERMATID STAGE OF SPERMATOGENESIS, ACCUMULATES IN SPERMATOZOA NUCLEI

We have described previously three mouse multifinger coding genes (C. Passananti et al., Proc. Natl. Acad. Sci. USA, 86: 9417-9421, 1989). W e have analyzed the expression of one of them, termed Mfg2 and renamed Zfp59, and demonstrated that Zfp59 mRNA and its translation product a re present in specific stages of mouse spermatogenesis. The predicted amino acid sequence of the Zfp59 protein has been found to consist of 16 zinc-finger motifs clustered at the COOH terminus and subdivided in to two groups by a degenerate finger motif. At its NH2 terminus, Zfp59 shares with other members of the zinc finger gene family two addition al conserved amino acid modules A and B, described as either FAX, KRAB , or FPB domains. By means of Northern blot, Western blot analysis, an d localization, Zfp59 mRNA and its translation product were shown to b e synthesized specifically during the postmeiotic phase of male germ l ine differentiation. By immunoelectron microscopy, the Zfp59 protein h as been shown to accumulate in the nuclei of mature sperms in associat ion with the nuclear matrix.